This invention relates generally to radio frequency antennas and more particularly to radio frequency antennas adapted to produce fan-shaped radiation patterns.
As is known in the art, a sectoral horn may be used to produce a fan-shaped radiation pattern. Such an antenna generally includes a rectangular waveguide, one end of which is flared in only one dimension. An electric field is produced within the horn, such field being aligned parallel to a pair of the four conductive walls defining such horn. Therefore, the electric field at the pair of walls becomes zero with the result that a cosine illumination, rather than the generally more desirable completely uniform illumination, is formed across the face of the horn. Further, the weight, fabrication cost and space occupied by such a sectoral horn sometimes limits the applications in which such horn may be used.